Diffusion brazing of Inconel 617 and 321 stainless steel by using AMS 4772 Ag interlayer

The diffusion brazing of Inconel 617 and AISI 321 stainless steel was carried out with a 50 mu m thick AMS 4772 Ag interlayer at a constant brazing temperature of 750 degrees C under a variable holding time (30 & 60 min). The microstructure of the diffusion-brazed joints was studied in detail via the use of a scanning electron microscope and energy dispersive spectroscopy. The shear strength and fracture behavior of the joints were investigated. Void-free diffusion-brazed joints were obtained due to the capillarity effect of Ag and a more uniform reaction layer was obtained in the joint with a higher brazing/holding time. The joint with a prolonged brazing time of 60 min has the maximum shear strength of 322.9 MPa and an improvement of 26 % over the joint processed at 30 min. The predominant brittle (fracture) failure in the sample processed at 30 min brazing/holding time was responsible for its weak shear strength. At effective brazing/holding time, the use of the AMS4772 Ag interlayer has been effective in joining the IN617 and AISI 321 SS alloys.